The following relates generally to wireless communication, and more specifically to an access procedure for an air-to-ground wireless communication system. Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communications system may include a number of ground stations, each simultaneously supporting communication for multiple mobile devices. Ground stations may communicate with an aircraft terminal (AT) on downstream and upstream links. Each ground station has a coverage range, which may be referred to as the coverage area of the cell. In an air-to-ground system, the distance between the AT and a ground station may be larger than the distance between a mobile device and a base station in other wireless communications systems. This separation may result in a significant delay between a transmission and a reception of the transmission. Such a delay may result in a transmission being lost if it is not received during the time slot allocated for reception of the transmission.
A large distance between the AT and the ground station may also make it difficult to achieve a high signal-to-noise ratio (SNR). One way to improve the SNR is for a transmitter to use beamforming techniques to direct more energy towards the receiver. However, for a ground station to use beamforming techniques to transmit data to an AT, it may be necessary for the ground station to have additional information about the AT.